Detective Sergeant Rob Brown said: "This type of incident can cause real disruption to the telephone network and deprive people of the use of their telephones and computers. It is essential the persons responsible for this irresponsible crime are brought to justice and prevented from committing similar acts in the future."

"BT takes these matters very seriously and we fully support the Met Police in their enquiries," BT security director Mark Hughes said. "We have decided to offer a reward for information to bring those people responsible for this, and similar incidents in the London area, to justice."

The Stepney Green burglars struck two weeks after thieves hit another London exchange in Mayfair. Gear reported to be worth millions was swiped while police and photographers thronged outside the pub next door, where Guy Ritchie was throwing a party to celebrate the release of his new film.